Set into the south-western side of the Monks' Graveyard, it is modest in every dimension: 0.63 metres tall, 0.3 metres wide, and just 0.06 metres thick. What makes it quietly remarkable is what it may once have been. The arms of this rough stone are broken, leaving its identification as a cross uncertain, a question mark in carved stone on one of Ireland's most celebrated early Christian sites.

The slab itself has an unusual profile, narrowing in width towards its base rather than sitting as a uniform upright. Whether that tapering was deliberate, shaped by the hand of a monk working sometime in the early medieval period, or whether it reflects the natural character of the stone, is not recorded. What survives is the object itself, catalogued by archaeologists Aidan O'Sullivan and Jerry Sheehan in their 1996 survey of the Iveragh Peninsula as item 948 in a comprehensive archaeological account of south Kerry. Skellig Michael, a UNESCO World Heritage Site, was occupied by a community of monks who constructed their remarkable dry-stone settlement, consisting of corbelled cells, an oratory, and a graveyard, on a vertiginous rock some twelve kilometres off the Kerry coast. The graveyard in which this slab stands would have marked the resting place of those who chose, or were sent, to live out their lives in that extraordinary isolation.